1. Field of the Invention
The present invention relates to a controller-assisted, manually shifted vehicular transmission system having an engine controller for controlling engine fueling in response to command signals. The controller normally will fuel the engine in accordance with the operator's throttle pedal position, but will override the operator if it is determined that assistance is required to complete a shift. In particular, the present invention relates to logic rules for controlling a transmission system of the type described, including determining when the operator's throttle setting is so inappropriate for completing a shift, such as a splitter shift, into a target gear ratio that the engine controller should override the operator and fuel the engine in a predetermined manner, regardless of throttle pedal position.
2. Description of the Prior Art
Compound manually shifted mechanical transmissions of the range, splitter and/or combined range/splitter type are in wide use in heavy-duty vehicles and are well known in the prior art, as may be seen by reference to U.S. Pat. Nos. 4,754,665; 5,272,929; 5,370,013 and 5,390,561, 5,546,823; 5,609,062 and 5,642,643, the disclosures of which are incorporated herein by reference. Typically, such transmissions include a main section shifted directly or remotely by a manual shift lever and one or more auxiliary sections connected in series therewith. The auxiliary sections most often were shifted by a slave actuator, usually pneumatically, hydraulically, mechanically and/or electrically operated, in response to manual operation of one or more master switches. Shift controls for such systems by be seen by reference to U.S. Pat. Nos. 4,455,883; 4,550,627; 4,899,607; 4,920,815; 4,974,468; 5,000,060; 5,272,931; 5,281,902; 5,222,404 and 5,350,561, the disclosures of which are incorporated herein by reference.
Fully or partially automated transmission systems wherein a microprocessor-based electronic control unit (ECU) receives input signals indicative of various system operating conditions and processes same according to logic rules to issue command output signals to one or more system actuators are known in the prior art, as may be seen by reference to U.S. Pat. Nos. 4,361,060; 4,593,580; 4,595,986; 4,850,236; 5,435,212; 5,582,069; 5,582,558; 5,620,392; 5,651,292 and 5,679,096; 5,682,790; the disclosures of which are incorporated herein by reference.
Prior art manually shifted vehicular transmission systems, including computer-assisted systems, are subject to improvement, as (i) the best pneumatic, hydraulic, electric or mechanical clutch engagement systems can be defeated if the driver does not get the engine to the proper synchronous speed and/or (ii) drivers do not like not being in control of engine fueling. In an upshift, if a driver reapplies fuel too early (prior to the jaw clutch engaging), the shift is missed because the application of fuel and subsequent engine speed increase drive the engine speed away from the desired synchronous speed, or if the engine deceleration is rapid, the clutch may not engage because the system passes through synchronous too quickly. In a downshift, if the driver does not apply enough fuel on the downshift to raise the engine speed to synchronous speed, the clutch does not engage, or if the driver applies too much fuel, the engine accelerates past the desired synchronous speed and the clutch does not engage. Excessive occurrences and lengthy duration of engine fueling not tracking throttle position also are objectionable to the vehicle driver.